Pix^® (mepiquat chloride) was applied in single and multiple applications to Determine optimum application rates and times on early maturing, stripper cotton on the Texas South Plains, and on late maturing, picker cotton in the Upper Texas Coast and Mississippi Delta.

In the Mississippi Delta, best plant height control was obtained from 20 g (ai/A) at 1st bloom, or 10 g (ai/A) Ist bloom + 10 g (ai/A) 3 weeks later, while on the Upper Texas Coast, best height control was observed from 10 g (ai/A) at ¼" square, and from 10 g + 10 g (ai/A) at ¼" square + 1st bloom. On the South Plains, where excessive vegetative growth is not normally a problem, the 10 g + 10 g (ai/A) at ¼" square + 1st bloom treatment provided best height control.

Doll numbers at defoliation were highest from 10 g + 10 g (ai/A) at ¼" square + 1st bloom in the Upper Coast, while boll numbers from this treatment and the 20g (ai/A) at 1st bloom treatment were highest in the South Plains.

Yields from Mississippi Delta studies indicate increases over the untreated control of from 9% for the 10 g (ai/A) at Ist bloom treatment to 12% for either 20 g (ai/A) at 1st bloom or 10 g + 10 g (ai/A) split at Ist bloom + 3 weeks. In Upper Texas Coast studies, highest total yields were obtained from 10 g (ai/A) at Ist bloom followed closely by yields from 10 g (ai/A) at ¼"square and 1.0 g + 10 g (ai/A) split produced higher yields than other treatments at 1st picking. In the South Plains, yields from the 10 g + 10 g (ai/A) at ¼" square + early bloom split application were slightly higher than other P x treatments and the untreated check.

The 1984 test results support the current Pix R cotton label. Further testing will be conducted by BASF Market Development in 1985.